1. Field of the Invention
The present invention relates to antimicrobial glass and methods for producing antimicrobial glass, and particularly to antimicrobial glass excellent in discoloration prevention effect and in discriminativity which contains an inorganic coloring agent, and to methods for producing antimicrobial glass.
2. Description of the Related Art
Recently, in the field of construction materials, home electric appliances (including television sets, personal computers, mobile telephones and video cameras), sundries, packaging materials, etc., there have been used antimicrobial resin compositions produced by mixing a predetermined amount of antimicrobial glass having a predetermined particle size into resin in order to impart an antimicrobial effect.
As such an antimicrobial resin composition, a synthetic resin molded body which contains, in the resin, a borosilicate antimicrobial glass capable of releasing silver ion is disclosed (see, for example, Patent Document 1).
More concretely, this synthetic resin molded body is constituted by containing, in a synthetic resin, a borosilicate antimicrobial glass containing 0.1 to 20 parts by weight of Ag2O as monovalent Ag in 100 parts by weight of glass solid formed of one or two or more kinds of network-forming oxides selected from the group consisting of SiO2, B2O3 and P2O5 and one or two or more kinds of network-modifying oxides selected from the group consisting of Na2O, K2O, CaO and ZnO. In the example of the patent publication, an antimicrobial glass is disclosed which contains, in a synthetic resin, an antimicrobial glass having an average particle diameter of 20 μm or less formed by adding 2 parts by weight of Ag2O to 100 parts by weight of a mixture formed of 40 mol % of SiO2, 50 mol % of B2O3 and 10 mol % of Na2O.
As an antimicrobial resin composition, a resin composition is disclosed which contains a scale-like, antimicrobial glass having a particle diameter of 10 to 1000 μm and a thickness of 0.1 to 20 μm (see, for example, Patent Document 2).
More specifically, the composition of the scale-like glass is composed of 20 to 60% by weight of SiO2, 30 to 70% by weight of B2O3, 5 to 35% by weight of Na2O and 0.5 to 3% by weight of Ag2O when containing B2O3, and 55 to 80% by weight of SiO2, 0.5 to 30% by weight of Al2O3, 19.5 to 42% by weight of Na2O and 0.5 to 3% by weight of Ag2O when containing no B2O3.
Moreover, a water-related antimicrobial product is disclosed which contains a silver ion-containing inorganic antimicrobial agent capable of producing an eluted amount of silver ion of 0.5 ng/cm2/day or more when it is immersed in boiling water at 100° C. for 500 to 1,000 hours and subsequently immersed in water or an acid at 20° C. for 24 hours, and an inorganic filler (see, for example, Patent Document 3).
More specifically, a water-related antimicrobial product is disclosed in which a silver ion-containing inorganic antimicrobial agent having an average particle diameter of 2 to 20 μm and containing 0 to 5% by weight of Ag2O to glass components composing of 56 to 59 mol % of P2O5, 33 to 38 mol % of MgO+CaO+ZnO and 6 to 8 mol % of Al2O3 are added in an amount within the range of 0.5 to 5% by weight, and further an inorganic filler is added in an amount within the range of 5 to 80% by weight.
Antimicrobial resin compositions are also proposed in which electric items, such as a dish washer, a dish dryer, a refrigerator, a washing machine and a pot, are provided as examples of the applications of an antimicrobial glass (see, for example, Patent Documents 4 to 6).
According to Patent Documents 4 to 5, that is, antimicrobial resin compositions are proposed which contain, in a molded resin constituting such electric items, an antimicrobial glass having an average particle diameter of 20 μm or less and composing of 40 to 80 mol % of ZnO, 5 to 35 mol % of SiO2 and 5 to 30 mol % of CaO, and an antimicrobial glass having an average particle diameter of 20 μm or less and composing of 54 to 60 mol % of ZnO, 25 to 32 mol % of B2O3, 7 to 12 mol % of SiO2 and 5 to 8 mol % of alkali metal oxide in predetermined amounts, respectively.
According to Patent Document 6, there is disclosed an antimicrobial glass wherein the maximum diameter (t1) of the antimicrobial glass is adjusted to a value within the range of 1 to 50 mm and the eluted amount of silver ion is adjusted to a value within the range of 0.5 to 100 mg/(g·24 hrs) and a silver ion containing water is prepared by bringing the antimicrobial glass into contact with water directly and a predetermined antimicrobial treatment is applied to a matter to be antibacterialized during or after washing. A method for the production thereof is also disclosed.
Furthermore, as an application of an antimicrobial glass, proposed is a glass water treating agent to be used in water treating apparatuses such as water tanks and cooling towers (see, for example, Patent Document 7).
This is a glass water treating agent which comprises a phosphoric acid-based glass having a maximum diameter of 10 mm or more, wherein the weight composition ratios are (RO+R2O)/P2O3=0.4 to 1.2 and R2O/(RO+R2O3)=0 to 10 (R is Ca, Na, etc.) and B/A≧⅓ where the initial dissolution rate is represented by A and the terminal dissolution rate is represented by B, and the content of metal ion is 0.005 to 5% by weight.    [Patent Document 1] JP1-313531A (Claims)    [Patent Document 2] JP7-25635A (Claims)    [Patent Document 3] JP10-72530A (Claims)    [Patent Document 4] JP2002-3238A (Claims)    [Patent Document 5] JP2002-3239A (Claims)    [Patent Document 6] WO2005/087675 (Claims)    [Patent Document 7] JP7-63701B (Claims)